1. Field of the Invention
The present invention relates to a method of tape bonding for bonding either bumps installed on a pellet or independent bumps to leads provided on a carrier tape.
2. Prior Art
In a conventional tape bonding method, bumps on pellets are bonded to leads of a carrier tape as disclosed, for example, in Japanese Patent Publication Nos. 57-53974, 62-27735 and 62-55298. In another conventional method, independent bumps are bonded to the leads of a carrier tape as disclosed, for example, in Japanese Patent Publication Nos. 62-31819 and 62-34142. In both of these methods, bonding of bumps to leads installed on a carrier tape is accomplished by pressing a bonding tool heated to approximately 600.degree. C. directly against the leads.
However, since the bonding tool is heated to a high temperature and is pressed directly against the leads, foreign materials such as copper oxide, tin plating, adhesive solvents, etc., are likely to adhere to the tip of the bonding tool.
In addition, bonding tools are generally made of an SUS alloy, and such alloys are susceptible to severe wear and adhesion of foreign materials. If a ruby is embedded in the tip of the bonding tool, the problem of wear is slightly alleviated, but there is no improvement in terms of adhesion of foreign materials. If a diamond is embedded in the tip of the bonding tool, wear is greatly reduced, but there is still no improvement in terms of the adhesion of foreign materials.
Accordingly, such bonding tools must be cleaned at regular intervals after a given number of uses. The frequency of cleaning varies depending upon the lead material; however, frequent cleaning after every 50 to 200 bonds is required. Thus, the productivity problems arise.